U.S. patent application number 17/327940 was filed with the patent office on 2021-12-02 for novel topical skin closure compositions and systems.
This patent application is currently assigned to Ethicon, Inc.. The applicant listed for this patent is Ethicon, Inc.. Invention is credited to Duan Li Ou.
Application Number | 20210371662 17/327940 |
Document ID | / |
Family ID | 1000005663472 |
Filed Date | 2021-12-02 |
United States Patent
Application |
20210371662 |
Kind Code |
A1 |
Ou; Duan Li |
December 2, 2021 |
Novel Topical Skin Closure Compositions and Systems
Abstract
Novel compositions and systems for closure of wounds are
disclosed. The compositions provide devices of improved flexibility
and elasticity and are readily applied to wound sites or over wound
closure devices. The present invention is also directed to a novel
platinum catalyst for use in such compositions. The catalyst
provides for rapid curing on topical surfaces such as skin and
bonds to such surfaces in about 2-5 minutes.
Inventors: |
Ou; Duan Li; (Warren,
NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ethicon, Inc. |
Somerville |
NJ |
US |
|
|
Assignee: |
Ethicon, Inc.
Somerville
NJ
|
Family ID: |
1000005663472 |
Appl. No.: |
17/327940 |
Filed: |
May 24, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16885361 |
May 28, 2020 |
|
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17327940 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08K 3/36 20130101; A61L
15/18 20130101; B01J 23/42 20130101; C08L 83/04 20130101; A61L
15/26 20130101; C08K 5/0025 20130101; C08K 5/5415 20130101 |
International
Class: |
C08L 83/04 20060101
C08L083/04; C08K 3/36 20060101 C08K003/36; C08K 5/00 20060101
C08K005/00; C08K 5/5415 20060101 C08K005/5415; B01J 23/42 20060101
B01J023/42; A61L 15/26 20060101 A61L015/26; A61L 15/18 20060101
A61L015/18 |
Claims
1. A composition comprising: a cross-linkable silicone polymer
having reactive functionalities; a silica-containing composition; a
silicone cross-linking agent; and, a catalyst, wherein said
catalyst comprises a platinum tetramethyldivinyl disiloxane diethyl
maleate complex having the formula:
Pt[(CH.sub.2.dbd.CH)(CH.sub.3).sub.2Si].sub.2O.(COCH.dbd.CHCO)(-
C.sub.2H.sub.5O).sub.2.
2. The composition of claim 1, wherein the cross-linkable silicone
polymer is selected from the group consisting of vinyl terminated
polydialkylsiloxane, vinyl terminated poly dimethylsiloxane, vinyl
terminated polydiphenylsilane-dimethylsiloxane copolymer, vinyl
terminated polyphenylmethylsiloxane, vinyl terminated
polyfluoropropylmethyl-dimethylsiloxane copolymer, vinyl terminated
polydiethylsiloxane, and SiH terminated polydimethyldisiloxane.
3. The composition of claim 1, wherein the cross-linkable silicone
polymer comprises vinyl terminated poly dimethylsiloxane.
4. The composition of claim 1, wherein the silica-containing
composition comprises a trimethyl silyl surface treated silica
filler.
5. The composition of claim 1, wherein the silica-containing
composition is selected from the commercially available reactive
silica-containing silicone bases including HCR (high consistent
rubber) bases and LSR (liquid silicone rubber) bases.
6. The composition of claim 5, wherein the silica-containing
composition is a liquid silicone rubber base.
7. The composition of claim 1, wherein the silicone cross-linking
agent is selected from the group consisting of
polymethylhydrosiloxane, polymethylhydro-co-polydimethylsiloxane,
polyethyhydrosiloxane,
polymethylhydrosiloxane-co-octylmethylsiloxane, and
polymethylhydrosiloxane-co-methylphenylsiloxane.
8. The composition of claim 1, wherein the silicone cross-linking
agent comprises polymethylhydrosiloxane,
polymethylhydro-co-polydimethylsiloxane and combinations
thereof.
9. The composition of claim 1, wherein the composition additionally
comprises about 0 wt. % to about 30 wt. % of an organic solvent,
based upon the weight of the composition.
10. The composition of claim 1, wherein the composition comprises
about 1 wt. % to about 15 wt. % of the silicone cross-linking agent
based on total solids, wherein the coating composition additionally
comprises about 0 wt. % to about 30 wt. % of an organic solvent,
based upon the weight of the coating composition.
11. The composition of claim 1, wherein the coating composition
comprises about 0.003 wt. % to about 0.06 wt. % of the platinum
catalyst, based on total solids, wherein the coating composition
additionally comprises about 0 wt. % to about 30 wt. % of an
organic solvent, based upon the weight of the coating
composition.
12. The composition of claim 1, wherein the coating composition
additionally comprises a solvent selected from the group consisting
of pentane, hexane, heptanes, mixtures of low molecular weight
olefins, and combinations thereof.
13. A composition comprising a platinum tetramethyldivinyl
disiloxane diethyl maleate complex having the formula:
Pt[(CH.sub.2.dbd.CH)(CH.sub.3).sub.2Si].sub.2O.(COCH.dbd.CHCO)(C.sub.2H.s-
ub.5O).sub.2
14. The coating composition of claim 1, wherein the composition is
curable at temperatures at about 19 C.
15. The coating composition of claim 14, wherein the composition is
curable at temperatures of about 28 C in about 2-5 minutes.
16. A kit comprising: a) a wound closure device; and b) the
composition of claim 1.
17. The kit of claim 16, wherein the wound closure device is a
wound closure strip.
18. The kit of claim 17, wherein the wound closure strip is
selected from the group consisting of meshes, polymeric films,
plastic foams (including open celled foam), woven fabrics, knitted
fabrics, a non-woven fabrics and combinations thereof.
19. The kit of claim 18, wherein the wound closure strip is a
mesh.
20. The kit of claim 19, wherein the wound closure device comprises
materials selected from the group consisting of polyesters, nylons,
acrylics, rayons, polyurethanes, polyurethane foams, polystyrenes,
polyesters, polyethylene terephthalate (PET), polyamides,
polylactic acids, polyglycolic acids, polycaprolactones, and
mixtures thereof; cotton, silk and linen; and surface-treated
materials that impart an OH functionality to their surfaces
including but not limited to OH surface-treated PTFE, OH
surface-treated polypropylene and OH-surface treated
polyethylene.
21. The composition of claim 1, comprising the combination of equal
volumes of a Part A and a Part B, wherein: Part A comprises 60 to
95 wt. % vinyl terminated polydimethyl silicone base polymer and
fumed silica particles, 5 to 15 wt. % vinyl terminated poly
dimethylsiloxane having a molecular weight ranging from 3,000 to
9,000, and 100 to 250 ppm of elemental platinum contributed from
the catalyst
Pt[(CH.sub.2.dbd.CH)(CH.sub.3).sub.2Si].sub.2O.(COCH.dbd.CHCO)(C.sub.2H.s-
ub.5O).sub.2; and Part B comprises 60 to 80 wt. % vinyl terminated
polydimethyl silicone base polymer and fumed silica particles, 10
to 40 wt. % polymethylhydro-co-polydimethyl siloxane cross linker,
and 3 to 12 wt. % hydride terminated poly dimethylsiloxane having a
molecular weight ranging from 3,000 to 9,000.
22. The composition of claim 1, comprising the combination of equal
volumes of a Part A and a Part B, wherein: Part A comprises 30-100
wt. % vinyl terminated polydimethyl silicone base polymer and fumed
silica particles, 5 to 15 wt. % vinyl terminated poly
dimethylsiloxane having a molecular weight ranging from 3,000 to
9,000, and 100 to 250 ppm of elemental platinum contributed from
the catalyst
Pt[(CH.sub.2.dbd.CH)(CH.sub.3).sub.2Si].sub.2O.(COCH.dbd.CHCO)(C.sub.2H.s-
ub.5O).sub.2; and Part B comprises 0 to 30 wt. % vinyl terminated
polydimethyl silicone base polymer and fumed silica particles, 10
to 40 wt. % polymethylhydro-co-polydimethyl siloxane cross linker,
and 3 to 12 wt. % hydride terminated poly dimethylsiloxane having a
molecular weight ranging from 3,000 to 9,000.
23. The composition of claim 1, comprising the combination of equal
volumes of a Part A and a Part B, wherein: Part A comprises 0 to 40
wt. % vinyl terminated polydimethyl silicone base polymer and fumed
silica particles, 5 to 15 wt. % vinyl terminated poly
dimethylsiloxane having a molecular weight ranging from 3,000 to
9,000, and 100 to 250 ppm of elemental platinum contributed from
the catalyst of
Pt[(CH.sub.2.dbd.CH)(CH.sub.3).sub.2Si].sub.2O.(COCH.dbd.CHCO)(C.sub.2H.s-
ub.5O).sub.2; and Part B comprises 70-100 wt. % vinyl terminated
polydimethyl silicone base polymer and fumed silica particles, 10
to 40 wt. % polymethylhydro-co-polydimethyl siloxane cross linker,
and 3 to 12 wt. % hydride terminated poly dimethylsiloxane having a
molecular weight ranging from 3,000 to 9,000.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application is a continuation-in-part of co-pending
U.S. Non-Provisional application Ser. No. 16/885,361 filed May 28,
2020, and is related to U.S. Non-Provisional application Ser. No.
16/885,413 (Attorney Docket No. ETH6068USNP1), Ser. No. 16/885,426
(Attorney Docket No. ETH6069USNP1), Ser. No. 16/885,366 (Attorney
Docket No. ETH6084USNP1), Ser. No. 16/885,375 (Attorney Docket No.
ETH6085USNP1), all filed on May 28, 2020 and U.S. Non-Provisional
application Ser. No. ______ (Attorney Docket Number ETH6084USCIP1,
concurrently filed herewith) and all of the foregoing patent
applications having a common assignee the contents of which are
herein incorporated by reference in their entirety for all
purposes.
TECHNICAL FIELD
[0002] The field of art to which this invention pertains is
silicone-based wound closure compositions and devices, in
particular, silicone-based topical skin adhesives (TSA's) and
systems.
BACKGROUND OF THE INVENTION
[0003] There is a need for elastomeric topical skin adhesives,
especially for skin closure of the moving body joints such as
knees, wrists, elbow, etc.
[0004] Elastic versions of the TSA are especially needed in
orthopedic surgery. Aggressive motion of joints may compromise the
quality of the closure at the interface between the adhesive and
the skin. Watertight closure is also desirable in a product in
order to lessen the possibility of post-surgical infections.
Silicone types of adhesives are one solution for both these two key
customer requirements due to its elasticity and sealing
properties.
[0005] Silicone is known for its inertness and commonly used as OTC
scar reduction products. Reducing skin reactions and improvement of
cosmesis are the extra benefits provided by silicone-based TSA.
[0006] Thus, there is a need for elastomeric topical skin
adhesives, especially for the closure of the moving body parts and
joints, such as knees, wrists, elbows, etc.
SUMMARY OF THE INVENTION
[0007] Accordingly, novel catalytic compositions, silicone based
curable adhesive compositions, and wound closure systems are
disclosed.
[0008] The compositions comprise a mixture of vinyl terminated
polydimethylsiloxane, and poly dimethylhydro-co-poly
dimethylsiloxane cross linker, surface treated silica particles as
bonding agent, and a novel, non-conventional platinum catalyst,
optionally with common low boiling point organic solvent such as
aliphatic organic solvent such as hexane or its commercial
derivatives, and SiH terminated polydimethyl siloxane chain
extender. The proposed silicone adhesive can be dried on skin at
body temperature in less than 3 minutes. The skin holding forces
between the proposed silicone adhesive and skin is comparable or
better than the typical cyanoacrylate-based TSA products. Unlike
the traditional cyanoacrylate-based TSA products, the invented
silicone-based TSA when combined with traditional wound closure
devices can be stretched to 160% of its original length and fully
recover to its original dimension.
[0009] The bonding formation is enabled by the condensation
reaction between the silanol functions on the surface of silica
particle and the OH functions on the skin. Silanol condensation
tends to be sluggish at ambient temperature and the novel
non-conventional catalyst enables this reaction to occur in a short
period of time. The platinum based novel catalyst also activates
vinyl silylation reaction to allow vinyl terminated silicone
polymer to cross link simultaneously to the condensation
reaction.
[0010] In one embodiment, the invention relates to a composition
comprising:
[0011] a cross-linkable silicone polymer having reactive
functionalities;
[0012] a silica-containing composition;
[0013] a silicone cross-linking agent; and
[0014] a catalyst, wherein said catalyst comprises a platinum
tetramethyldivinyl disiloxane diethyl maleate complex having the
formula:
Pt[(CH.sub.2.dbd.CH)(CH.sub.3).sub.2Si].sub.2O.(COCH.dbd.CHCO)(C.sub.2H.-
sub.5O).sub.2.
[0015] In the foregoing embodiment, the silica-containing
composition may be added as a separate component, but more
preferably it is contained in the cross-linkable silicone polymer.
The coating compositions may also contain a platinum catalyst.
[0016] Another aspect of the present invention is a medical device
having a surface, wherein at least part of the surface is coated
with the above-described novel silicone coating composition.
[0017] Still yet another aspect of the present invention is a novel
platinum catalyst for use with cross-likable silicone coatings. The
catalyst comprises a platinum complex having the following
formula:
Pt[(CH.sub.2.dbd.CH)(CH.sub.3).sub.2Si].sub.2O.(COCH.dbd.CHCO)(C.sub.2H.-
sub.5O).sub.2.
[0018] A further aspect of the present invention is use of the
compositions of this invention as a topical skin adhesive and as a
topical skin adhesive in conjunction with wound closure devices as
systems or kits to close wounds.
[0019] In other embodiments, the compositions of this invention are
made under controlled viscosity requirements limiting or
eliminating the need for organic solvent(s) as hereinafter
described.
[0020] These and other aspects and advantages of the present
invention will become more apparent from the following
description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is an NMR peak comparison of the Karstedt Catalyst
compared with the NMR peak of the novel catalyst of this
invention.
[0022] FIGS. 2A, 2B and 2C show the steps of a stretch test used to
demonstrate to elasticity of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0023] The terms silicone and siloxane are conventionally used
interchangeably in this art, and that usage has been adopted
herein.
[0024] Topical Skin Adhesive Compositions & Wound Closure
Systems
[0025] One aspect of the present invention is directed to novel
wound closure compositions which are particularly useful for
closing lacerations and surgical incisions. These compositions are
suitable for use as topical skin adhesives and as adhesives in
conjunction with wound closure devices.
[0026] In one embodiment, the compositions include a mixture of a
cross-linkable siloxane polymer and a silica-containing composition
which may be added as a separate component, but more preferably
contained in the cross-linkable silicone polymer, a conventional
silicone cross-linking agent, and a platinum catalyst. The silicone
polymer components are blended with conventional aromatic organic
solvents, including, for example, aliphatic organic solvents (such
as, for example, hexane, heptane or its commercial derivatives) to
form coating solutions or compositions. Other solvent suitable for
coating solution includes and not limited to low molecular weight
siloxane, e.g., hexamethyldisiloxane.
[0027] The cross-linkable siloxane polymers useful in the
compositions of the present invention will have reactive
functionalities or terminal functional groups, including but not
limited to vinyl terminated, hydroxyl and acrylate functional
groups. The cross-linkable siloxane polymers that can be used in
the compositions of the present invention preferably include vinyl
terminated polydialkylsiloxane or vinyl terminated
polyalkyarylsiloxane. Examples include but are not limited to the
following vinyl terminated siloxane polymers: polydimethyl
siloxane, poly diphenylsilane-dimethylsiloxane copolymer,
polyphenylmethylsiloxane, polyfluoropropylmethyl-dimethylsiloxane
copolymer and polydiethylsiloxane. It is particularly preferred to
use vinyl terminated cross-linkable polymethyl siloxane.
[0028] The cross-linking agents that can be used in the
compositions of the present invention include conventional silicone
cross-linking agents such as, for example, polymethylhydro
siloxane, polymethylhydro-co-polydimethylsiloxane, polyethyhy
drosiloxane, polymethylhydrosiloxane-co-octylmethylsiloxane,
polymethylhydrosiloxane-co-methylphenylsiloxane. The preferred
conventional crosslinkers for use in the compositions of the
present invention are polymethylhydro siloxane and
polymethylhydro-co-polydimethylsiloxane. Precise control of
cross-link density in the coatings of the present invention is
achieved by precise control of the ratio of non-cross-linkable
silicone polymer (e.g., polydimethylsiloxane) to fully cross-linked
polymer. The fully cross-linked polymer is formed by a reaction
between the functionalized cross-linkable polymer and the
cross-linking agent, for example, a vinylsilylation reaction
between vinyl-terminated polydimethylsiloxane and
polymethylhydrosiloxane optionally in the presence of a platinum
complex catalyst. Examples of this polymer include but are not
limited to: Gelest Product Code No. DMS-V31, DMS-V33, DMS V-35, DMS
V42, DMS-V46, DMS-V52, etc., available from Gelest, Inc.,
Morrisville, Pa. 19067. The typical molecular structure of vinyl
terminated poly dimethyldisiloxane is the following:
##STR00001##
wherein n is defined by the molecular weight.
[0029] The molecular weights of the silicone polymers used wherein
can be estimated based on the relationship between viscosity and
molecular weight (page 11, SILICONE FLUIDS: STABLE, INERT MEDIA
ENGINEERING AND DESIGN PROPERTIES, Catalog published by Gelest,
Inc. 11 East Steel Rd. Morrisville, Pa. 19067). Using A. J. Barry's
relationship for molecular weights (M) >2,500 correlating the
kinematic viscosity .mu. expressed in centistokes (cSt) at 25 C,
the molecular weight M of silicones can be estimated as
follows:
log .mu..sub.cSt=1.00+0.0123M.sup.0.5
(as published by A.J. Barry in the Journal of Applied Physics 17,
1020 (1946))
[0030] Vinyl terminated polydimethylsiloxane reacts with
polymethylhydrosiloxane cross-linker in the presence of platinum
catalyst under appropriate conditions; the vinyl terminated
polydimethylsiloxane linear polymers are fully cross-linked to each
other as the result of this reaction. The amount of
polymethylhydrosiloxane cross-linker is in large stoichiometric
excess compared to vinyl terminated polydimethylsiloxane base
polymer. It is believed that the extra SiH functions in the
cross-linker react with the OH functions on the surface such as
human skin, e.g., polymeric sutures, to form Si--O--C bonds at
elevated temperature or in the case of steel needles, to form
Si--O--Fe bonds. Covalent bonds thus created between the silicone
coating and the device, as the result of this reaction, result in
the adhesive attachment of the coating to a given surface.
[0031] The polymethyhydrosiloxane cross-linkers, or cross-linking
agents, used in the practice of the present invention will have a
molecular weight between about 1000 and about 3000, and preferably
between about 1400 and about 2100. An example of this polymer
cross-linker includes, but is not limited to, Gelest Product Code
No. HMS-991, HMS-992, available from Gelest, Inc., Morrisville, Pa.
19607. The typical molecular structure of the
polymethylhydrosiloxane cross-linker is the following:
##STR00002##
wherein n is defined by the molecular weight.
[0032] Polymethylhydro-co-polydimethylsiloxane can also be used as
cross-linker or cross-linking agent in the novel coatings of the
present invention. Examples of this polymer include, but are not
limited to, Gelest Product Code No. HMS-301, HMS-501. The molecular
weight of this siloxane polymer cross-linking agent will typically
be between about 900 and about 5,000, and preferably about 1,200 to
about 3,000. The typical molecular structure of
polymethylhydro-co-polydimethylsiloxane cross linker is the
following:
##STR00003##
wherein n and m are defined by the molecular weight.
[0033] Silica-Containing Compositions
[0034] As used herein, the silica-containing compositions described
for use with this invention include silica materials as a separate
component (such as surface treated silica) or from commercially
available compositions that contain silica in a cross linkable
silicone polymer mixture.
[0035] As a separate component, silica is incorporated into
composition of this invention to act as a bonding agent to skin and
other substrate materials. It is believed that the OH groups on the
surface of silica particles react with the OH functions on the
surface of substrate material including human skin under a certain
condition, as illustrated below.
##STR00004##
[0036] Silica particles were incorporated into the cross linkable
silicone polymers. Hexamethyl silyl surface treatment is needed for
the silica particles to enable its compatibility to the
polysiloxane polymer matrix which prevents phase separation. An
example of treated silica includes hexamethyldisilazane treated
silica i.e., trimethyl silyl surface treated silica filler (Gelest
SIS6962.0).
[0037] In the case of silicone polymers already containing silica,
these may be obtained from commercially available sources such as
silica-containing composition selected from reactive
silica-containing silicone bases including HCR (high consistent
rubber) bases and LSR (liquid silicone rubber) bases, preferred are
LSR bases. Other commercial examples of this material include and
is not limited to Wacker 401-10, 401-20, 401-40 base; and a liquid
silicone rubber base, a commercial example of this material
includes and is not limited to Bluestar Silbione LSR 4370 base.
These type of commercial silicone rubber bases are prepared by
mixing a surface-treated silica filler with various molecular
weights of vinyl terminated polydimethylsiloxane polymer. In-situ
surface treatment may be performed during the mixing process to
improve the compatibility between filler and polysiloxane
polymer.
[0038] Catalyst
[0039] Karstedt of GE Silicone invented a highly active platinum
catalyst at the beginning of the 1970's (U.S. Pat. No. 3,775,452).
Vinyl terminated polydimethylsiloxane can react with
polymethylhydrosiloxane containing cross linker in less than 1
minute at ambient temperature with as little as 10 ppm of the
Karstedt catalyst. The traditional platinum catalyst does not
enable the reaction between OH groups on the surface of silica
particles reacts and the OH functions on the surface of substrate.
This type of condensation reaction tends to be slow at ambient
condition and the typical catalyst for this reaction including
organic amine and catalyst such as tin dilaurate. Trace amount of
condensation catalyst will terminate the catalytic ability of
platinum catalyst which is referred as platinum poisoning in the
silicone industry. A novel platinum comparable catalyst is needed
to activate the OH condensation between silica particle and
substrate material, to enable rapid adhesion formation between
silicone and a given substrate material. A platinum based novel
catalyst of the present invention is able to activate both vinyl
silylation and OH condensation simultaneously.
[0040] The novel catalyst is prepared by reacting Karstedt's
catalyst with diethyl maleate according to scheme 1. The novel
platinum tetramethyldivinyl disiloxane diethyl maleate catalyst
enables both vinyl silylation and condensation reaction. This is
referred to as "dual functional silicone catalyst".
##STR00005##
[0041] The novel catalyst of the present invention may be prepared
in the following manner. Karstedt catalyst in xylene solution is
mixed with a low concentration of vinylcyclohexanol in a xylene
solution at ambient temperature for a sufficiently effective time
to complete the reaction, e.g., a half an hour, and completion of
the reaction is indicated by a change of the color of the reaction
mixture, from clear to light brown.
[0042] The resulting catalyst solution containing the novel
catalyst of the present invention is ready to use in a composition
useful as a topical skin adhesive. The formula of the resulting
platinum complex catalyst (platinum tetramethyldivinyl disiloxane
diethyl maleate complex) is.
Pt[(CH.sub.2.dbd.CH)(CH.sub.3).sub.2Si].sub.2O.(COCH.dbd.CHCO)(C.sub.2H.-
sub.5O).sub.2.
[0043] It should be noted that the resulting catalyst reaction
mixture will contain a small amount of the reaction product
divinyltetramethyldisiloxane. This component does not affect the
catalyst and is a low boiling point component that is rapidly
evaporated. Accordingly, purification of the catalyst mixture to
remove divinyltetramethyldisiloxane is optional, and it is believed
that its presence at ultra low concentrations will not affect the
cross-linking reaction of a cross-linkable silicone polymer. The
novel catalyst of the present invention also actives the bonding
formation between silanol groups on the surface of silica fillers
and OH functions on a given surface, that is, the catalyst is
capable to activate two reactions. This allows for curing the
cross-linkable components in silicone coatings to rapidly form
coating films at desired curing temperatures and provides bonding
to a given substrate such as human skin.
[0044] Solvents for Viscosity Reduction
[0045] Some commercially produced filler reinforced cross linkable
silicone polymers (silicone base rubber) have high viscosity,
typically higher than 500,000 and up to many millions of cP. It is
impossible to mix and spread such high viscosity material onto skin
and low hazardous organic solvent is needed to reduce its
viscosity.
[0046] Low temperature aliphatic solvents are used for this
purpose. Typical examples include, but are not limited to,
pentanes, heptanes, hexanes and their mixtures. The organic
solvents are added at a concentration sufficient to allow effective
blending of the silicone polymer components into a homogeneous
solution. The total solvent concentration is between 10% and 30%,
depending upon the original viscosity of the base rubber. Ultra-low
boiling point solvent such as n-butane and isopentane can also been
used to provide sprayable formulation of silicone adhesive.
[0047] Chain Extender for Low Viscosity Vinyl Terminated
Polydimethylsiloxane Base Polymer
[0048] For those commercially produced filler reinforced cross
linkable silicone polymers (silicone base rubber) that have a high
viscosity in the range from 100,000 centipoise (cP) to several
million cP (e.g., 1-20 million cP) viscosity, (low molecular
weight) vinyl terminated polydimethylsiloxane (<300 cP) may be
also added together with low temperature aliphatic solvents to
improve its mixability and spreadability. A SiH terminated
polydimethylsiloxane is added as a chain extender to polymerize the
low molecular weight vinyl terminated polydimentylsiloxane. The SiH
terminated polydimethylsiloxane base polymer has molecular weight
between 1000 and 100,000, preferably between 3,000 to 10,000.
Examples of this type of polymer include, but are not limited to:
Gelest Product Code No. DMS-H21, DMS-H31, etc. The typical
molecular structure of SiH terminated polydimethyldisiloxane is
illustrated below
##STR00006##
[0049] The above silicone polymers and novel platinum catalyst are
dispersed into low boiling point organic solvents to form the
coating solution. Low temperature aliphatic solvents are used for
the silicone dispersion. Aromatic solvents and hexamethyldisiloxane
are commonly used for silicone dispersion. Typical examples
include, but are not limited to, pentane, heptanes, hexane and
their mixtures. The organic solvents are added at a concentration
sufficient to allow effective blending of the silicone polymer
components into a homogeneous coating solution. The total solvent
concentration is from about 80 wt. % to about 99 wt. %, and is more
typically from about 85 wt. % to about 93 wt. %, depending upon the
coating thickness requirement. Those skilled in the art will
appreciate that the coating thickness can be engineered by changing
the solids content of the coating solution.
[0050] The sequence of the addition of components is important. The
typical coating composition is prepared in the following manner. In
the case when the silica is added as a separate component, the
vinyl terminated polydimethylsiloxane is dispersed into the first
solution such as hexamethyldisiloxane together with surface treated
silica for up to two hours until fully homogeneous (solution 2).
Heptane is then added (solution 3) and further mixing for one hour
prior to the addition of polymethylhydrosiloxane cross linker. The
solution is fully blended for one more hour after all of the
catalyst is added as the final component
[0051] In the following paragraph, the wt. % is the wt. % of total
solid content in the coating solution. The novel coating
compositions of the present invention will contain sufficient
amounts of the polymeric components, silica-containing composition,
cross-linking agent, catalyst, and solvent to effectively provide a
silicone coating having high flexibility and durability.
[0052] Typically, the amount of the silica in the coating solution
will be about 5 wt. % to about 40 wt. % (total solids), more
typically about 10 wt. % to about 30 wt. % (total solids), and
preferably about 15 wt. % to about 25 wt. % (total solids). The
amount of the cross-linkable silicone polymer will typically be
about 60 wt. % to about 95 wt. % (total solids), more typically
about 70 wt. % to about 90 wt. % (total solids), and preferably
about 75 wt. % to about 85 wt. % (total solids). The amount of the
silicone cross-linking agent will typically be about 1 wt. % to
about 15 wt. % (total solids), more typically about 2 wt. % to
about 10 wt. % (total solids), and preferably about 3 wt. % to
about 8 wt. % (total solids). The amount of the platinum catalyst
based upon the total solids in the novel silicone coating
compositions (platinum element in total solids) of the present
invention will typically be about 0.06 wt. % to about 0.003 wt. %,
more typically about 0.04 wt. % to about 0.008 wt. %, and
preferably about 0.03 wt. % to about 0.01 wt. %.
[0053] The amount of organic solvent in the compositions of the
present invention will typically be about 0 wt. % to about 30 wt.
%, more typically about 10 wt. % to about 20 wt. %, and preferably
about 12 wt. % to about 18 wt. %. Those skilled in the art will
appreciate that the amount of solvent present in the novel coating
compositions of the present invention will vary with several
factors, and that the solvent quantity in the coating compositions
will be selected to engineer an efficacious coating. The factors
typically considered include the method of application, the method
of cure, the coating equipment utilized, ambient conditions,
thickness, etc. It will be appreciated that each of the components
of the coating compositions of the present invention may consist of
blends of those components. For example, two or more cross-linkable
silicone polymers having different functionalities and/or molecular
weights may be used, etc.
[0054] The compositions of this invention are well suited for wound
closure applications such as topical skin adhesives. Generally,
these compositions have been demonstrated to cure to a non-tacky
nature or touch at temperatures at about 19 C. At temperatures of
about 28 C, the compositions cure in about 2-5 minutes.
[0055] As noted above and as would be appreciated by one of skill
in the art, the silicone compositions of this invention cure in
several minutes to films that are neither sticky nor tacky. In
contrast, some silicone adhesives, such as silicone pressure
sensitive adhesives (PSA's), are by nature sticky or tacky and are
intended to be such for the entire usable life of the adhesive.
Such useable life of the tacky silicone PSA's may be upwards to
several years. The non-tackiness of the compositions and examples
of this invention is measured by ASTM C679.
[0056] In general ASTM C679 consists of lightly touching a surface
of a curing sealant with a polyethylene film at regular intervals
until the sealant does not attach itself to the film and the film
appears clean when peel from the surface. More specifically a strip
of polyethylene film is placed on the surface of the curing
elastomer and a 30 g weight is placed on the film. The weight is
left in place for 30 seconds, then removed and the polyethylene
strip is removed and examined for sealant attachment to the film.
The length of time from when the sealant was first applied onto a
given surface until the time the sealant is no longer picked up by
the film is called tack-free time and is the time point at which
the film exhibits a non-tacky nature which evidences that the
sealant has cured.
[0057] Upon curing the curable compositions of the present
invention exhibit stretchable, flexible and elastic properties
especially useful for applications over wound closure on bendable
joints, such as knees, elbows. The curable compositions of the
present invention, optionally in combinations with various wound
closure devices can be applied over any wound closures, including
wounds over bendable joints or wounds not over bendable joints,
such a general surgical closures such over any tissue area, e.g.
body, abdominal, arm, leg, shoulder, back areas and similar.
[0058] The compositions of this invention can be applied onto
wounds directly as a curable liquid or semi-liquid, flowable
composition, or applied over a porous, flowable
composition-permeable wound closure device.
[0059] Wound Closure Systems
[0060] As noted above, the compositions of this invention are
suitable for use in combination with wound closure devices.
[0061] Wound closure devices suitable for use in this invention
comprise any device that is configured to close a wound. The wound
closure devices most useful are wound closure strips, tapes,
patches or any other materials suitable for closing a wound, most
preferably a strip. Preferably, the wound closure device is porous
and will allow a flowable, polymerizable adhesive to permeate the
device and to allow adequate bonding of the device to a tissue
surface being bonded.
[0062] The wound closure device comprises a wound facing side and a
top side. The wound facing side may further comprise an adhesive
such as a pressure sensitive adhesive (PSA) applied over at least a
portion of the wound facing side. The PSA is useful for initially
approximating the wound. The wound closure device is preferably
porous. By "porous" is meant herein either that the bulk of the
wound closure device has pores, such that subsequently applied
polymerizable adhesive composition is soaked up or absorbed by the
bulk material, or that the bulk of the wound closure device has
voids (like a net or screen), such that the subsequently applied
polymerizable adhesive composition passes directly through the bulk
material, with or without being soaked up or absorbed by the bulk
material. For example, in the case of textile materials, "porous"
is generally used to mean that the applied adhesive composition
permeates and passes through interstices between the fibers, but
does not necessarily pass into and through the fibers themselves.
Preferably the wound closure device is a mesh strip.
[0063] Such porosity (or other properties such as hydrophobicity or
hydrophilicity) will also allow a polymerization initiator or rate
modifier to be loaded in or on the wound closure device prior to
use, to initiate the subsequently applied polymerizable adhesive
composition. Such porosity will also preferably allow air and fluid
to pass through the wound closure device, either through pores per
se, or through voids in the bulk material. Depending upon the
degree of porosity and/or the size of the openings, such porosity
of the mesh or ability of air and fluid to permeate through the
mesh may be tailored either to remain after a final composite
material is formed, or to be absent therefrom. The wound closure
device is also preferably non-toxic, as it is intended to be used
cover a wound, such as on biological tissues. As such, the wound
closure device should be biologically compatible with the desired
substrate (such as tissue, skin, organ, or the like), and is
preferably a material that is governmentally approved or generally
regarded as safe for the desired purpose. By way of example,
suitable wound closure devices are mesh materials and are disclosed
in United States Patent Applications 2006/0009099 and 2005/0182443,
incorporated herein by reference in their entirety.
[0064] The wound closure device may be a textile or mesh/web
material. Suitable textile materials may be formed of either
synthetic or natural materials. Such textile material may be formed
of either woven or non-woven fabrics or materials. The wound
closure device may be, for example, any suitable polymeric film,
plastic foam (including open celled foam), a woven fabric, knitted
fabric, a non-woven fabric, mixture thereof, or the like. In
particular, suitable wound closure devices may thus be prepared,
for example, from nylons, polyolefins such as polyethylene,
polypropylene, ethylene propylene copolymers, and ethylene butylene
copolymers, acrylics, rayons, polyurethanes, polyurethane foams,
polystyrenes, plasticized polyvinylchlorides, polyesters such as
polyethylene terephthalate (PET), polyamides, polylactic acids,
polyglycolic acids, polycaprolactones, copolymer mixtures of the
above, natural materials such as cotton, silk and linen,
polytetrafluoroethylene (PTFE), biovascular material, collagen,
Gore-Tex.RTM., DACRON.RTM., etc. The preferred wound closure device
materials are those that contain an OH functionality on its surface
whether occurring naturally or by surface treatment to impart an OH
functionality ("OH surface-treated"). These materials include and
are not limited to polyesters, nylons, acrylic, rayon,
polyurethanes, polyurethane foams, polystyrenes, polyesters,
polyethylene terephthalate (PET), polyamides, polylactic acid,
polyglycolic acid, polycaprolactone, copolymer mixtures of the
above, and cotton, silk and linen. Suitable OH surface-treated
materials that impart an OH functionality to their surfaces include
but are not limited to OH surface-treated PTFE, OH surface-treated
polypropylene and OH surface-treated polyethylene.
[0065] The wound closure device may be formed of a synthetic,
semi-synthetic, or natural organic material. Thus, for example, the
mesh may be formed of a synthetic or natural polymer material, but
not from a material such as metal (such as silver, steel or the
like) or glass or ceramic. The wound closure device may be either
biodegradable, or not biodegradable. The wound closure device is
preferably resistant to tearing.
[0066] The thickness of the wound closure device may be from about
0.1 mm to about 25 mm. In another embodiment, the thickness of the
wound closure device is from about 0.5 mm to about 20 mm,
preferably from about 0.7 mm to about 10 mm, most preferably from
about 1 mm to about 5 mm.
[0067] When the wound closure device is a strip, the strip may be
from about 2 cm to about 40 cm, preferably from about 10 to about
30 cm, most preferably 25 cm in length. The strip may be from 0.1
to about 8 cm, preferably from about 2 to 6 cm, more preferably
about 4 cm in width.
[0068] The wound closure device may be selected to be elastic or
have some memory effect. In such embodiments, the elastic
properties of the mesh may desirably provide a degree of pressure
or stress at the application site, for example, to maintain wound
edge approximation.
[0069] Likewise, in embodiments where such additional degree of
pressure or stress at the application site is not desired, the mesh
may be selected to have less or no elasticity.
[0070] The wound closure device may be either biodegradable, or not
biodegradable. By "biodegradable" is meant that the mesh
biodegrades over time in vivo, such that it does not require
physical removal of the mesh after a set period of time. Thus, for
example, a biodegradable mesh is one that, in the in vivo
environment, will biodegrade over a period of from about one week
to about five years. A nonbiodegradable material is one that does
not biodegrade in an in vivo environment within about five years.
Such a nonbiodegradable material thus would require physical
removal of the wound closure device at a desired time, rather than
slowly deteriorating over time or may slough off naturally from the
tissue.
[0071] The wound closure device may include one or more chemical
materials located in or on it. For example, one or more chemical
substances may be dispersed in or on the wound closure device, such
as being chemically bound, physically bound, absorbed, or adsorbed
to it. Such chemical materials that may be present in or on the
wound closure device include, but are not limited to, any suitable
and preferably compatible additive that enhances performance of the
composite structure. Such additional chemical substances may be
bioactive or non-bioactive.
[0072] Suitable other chemical substances thus include, but are not
limited to, colorants (such as inks, dyes and pigments), scents,
protective coatings that do not chemically detach, temperature
sensitive agents, drugs, wound-healing agents, anti-microbial
agents and the like.
EXAMPLES
Example 1, Novel Platinum Catalyst (Synthesis Procedure)
[0073] 44.50 g of Gelest SIP 6831.2 (2.2% platinum divinyl
tetramethyldisiloxane complex in xylene, Karstedt catalyst) was
mixed with 2 g of diethyl maleate for 24 hours at ambient
temperature. Samples were taken out after 3 hours, 18 hours, and 24
hours for NMR testing and the NMR spectra for the 3 hour sample is
shown in FIG. 1.
[0074] The formation of the novel catalyst is the evidence for
scheme 1, which rests on NMR spectroscopic identification. Karstedt
catalyst is known with a characteristic .sup.195Pt signal at
approximately -6111 ppm.
[0075] After 3 hours of mixing of the mixtures of Example 1, a new
.sup.195Pt signal at -6082 ppm was observed along with the original
signal for the Karstedt catalyst at -6111 ppm as illustrated in the
NMR spectra of this mixture at 3 hours in FIG. 1. The intensity of
the new signal increases over time while the intensity of the
Karstedt catalyst signal reduced at the same time.
Example 2, Preparation of Silicone-Based Topical Skin Adhesive
[0076] In general and similar to most of commercially available
platinum cured silicone materials, the silicone-based topical skin
adhesive is delivered in a two-part kit by mixing equal volumes of
the Part A and Part B components.
[0077] As an overview, vinyl terminated polydimethylsiloxane is
mixed with Platinum tetramethyldivinyl disiloxane diethyl maleate
catalyst, silica particles and optionally aliphatic organic solvent
using a high-speed mixer to form part A of the kit. Vinyl
terminated polydimethylsiloxane were mixed with
polymethylhydro-co-polydimethylsiloxane cross linker, silica
particle and optionally aliphatic organic solvent using high speed
mixer to form part B of the kit.
[0078] Equal amounts of the two-part kit were mixed using a static
mixer and then spread onto the surface of a substrate, such as
skin. The mixture of the two-part kit cured within 5 minutes at
body temperature as determined by the loss of stickiness or
tackiness of the applied silicone.
[0079] Part A
[0080] 40 g of vinyl terminated polydimethylsiloxane (Gelest
DMSV41) was mixed with 10 g of surface treated silica particles
(Gelest SIS6962.0), together with 2.6 g of the resulting catalyst
of Example 1 using a high-speed centrifugal mixer (FlackTek DAC150
FV-K) at 3470 rpm for 5 minutes.
[0081] Part B
[0082] 40 g of vinyl terminated polydimethylsiloxane (Gelest
DMSV41) was mixed with 10 g of surface treated silica particles
(Gelest SIS6962.0), together with 3.34 g of
Polymethylhydro-co-polydimethylsiloxane (Gelest HMS301) using a
high-speed centrifugal mixer (FlackTek DAC150 FV-K) at 3470 rpm for
5 minutes.
Example 3, Preparation of Silicone-Based Topical Skin Adhesive
Using Commercial Silica-Containing Silicone Raw Material
[0083] Part A
[0084] 90 g of E-Kem 44 experimental base (containing vinyl
terminated polydimethyl silicone base polymer and fume silica
particles) was mixed with 4.72 g of the resulting catalyst of
Example 1, 9.0 g of low molecular weight vinyl terminated
polydimethyl silicone base polymer (Gelest DMS V21) and 26 g of
hexane using a high-speed centrifugal mixer (FlackTek DAC150 FV-K)
at 3470 rpm for 5 minutes.
[0085] Part B
[0086] 81 g of E-Kem 44 experimental base (containing vinyl
terminated polydimethyl silicone base polymer and fume silica
particles) was mixed with 8.1 g of polymethyl hydro siloxane cross
linker (Gelest DMS H991), 2.7 g of SiH terminated
polydimethylsiloxane chain extender (Gelest DMS H21) and 10.2 g of
hexane using a high speed centrifugal mixer (FlackTek DAC150 FV-K)
at 3470 rpm for 5 minutes.
Control Example: Control Example without Silica Bonding Agent and
Using Conventional Karstedt Catalyst
[0087] Part A
[0088] 40 g of vinyl terminated poly dimethylsiloxane (Gelest
DMSV41) was mixed with 2.6 g of Karstedt catalyst xylene solution
(1% of Gelest SIP 6831.2 in xylene) using a high-speed centrifugal
mixer (FlackTek DAC150 FV-K) at 3470 rpm for 5 minutes.
[0089] Part B
[0090] 40 g of vinyl terminated polydimethylsiloxane (Gelest
DMSV41) was mixed 3.34 g of Polymethylhydro-co-polydimethylsiloxane
(Gelest HMS301) using a high-speed centrifugal mixer (FlackTek
DAC150 FV-K) at 3470 rpm for 5 minutes.
Example 4, Preparation of Test Samples and Description of Test
Procedures
[0091] Test Procedures
[0092] Wound Closure Strip Testing Sample Preparation:
[0093] An 8 inch by 11 inch synthetic substrate (or bio substrate)
was cut in two halves with dimensions of 4 inches by 11 inches. A 1
inch wide PSA (pressure sensitive adhesive) coated polyester mesh
was placed along the cutting line to hold the two half pieces
together. The two-part silicone TSA compositions described above
were mixed and applied onto the mesh evenly to cover the entire
area of the mesh using a conventional rubber spatula.
[0094] Holding Strength Test:
[0095] This test evaluated the force required to separate the
substrate approximated with the PSA coated mesh and the applied
silicone TSA compositions. This method was based on ASTMF2458:
Standard test method for wound closure strength in tissue adhesive
and sealant.
[0096] Synthetic substrate (Mylar) were used for the test, selected
samples were also tested on porcine skin. The width of the
synthetic substrate was 1 inch and porcine skin was 2 inch and the
strain rate was 20 inches/minute.
[0097] Peel Test.
[0098] The T-peel strength test was performed following ASTM F2256:
Standard test method for Strength Properties of Tissue Adhesives in
T-Peel by Tension Loading.
[0099] The average peel strength of mesh coated with silicone-based
TSA in T-peel configuration is performed at a strain rate of 10
inches/minute.
[0100] Holding Strength Test Sample
[0101] Synthetic substrate, Polyester film (0.05 inch thick
Duralar.RTM. film), Grafix Plastics, Maple Heights, Ohio
[0102] An 8 inch by 11 inch piece of the Duralar.RTM. polyester
film was cut in two half with dimensions of 4 inch by 11 inch. A1.5
inch wide PSA (pressure sensitive adhesive) coated polyester mesh
(Lot #16204, Innovize, St Paul, Minn.) was placed along the cutting
line to hold the two half pieces together. The two-part silicone
TSA compositions in each of the following examples were
respectively mixed (Example 2, Example 3 and Control Example) and
evenly applied onto the mesh to cover the entire area of the mesh
using a conventional rubber spatula. The samples were dried between
2 to 5 minutes at 31 C. 5, 1 inch wide strips of each of the
covered mesh samples were cut for testing.
[0103] Bio Substrate (Porcine Skin)
[0104] A 2 inch by 8 inch sample of porcine skin was cut in two
halves with the dimensions of 2 inches by 4 inches. A 1.5 inch wide
PSA (pressure sensitive adhesive) coated polyester mesh was placed
along the cutting line to hold the two half pieces together. The
two-part silicone TSA composition was mixed (Example 3) and evenly
applied onto the mesh to cover the entire area of the mesh using a
conventional rubber spatula.
[0105] Peel Test Sample
[0106] Synthetic Substrate (Polyester Film, 0.05 Inch Thick
Duralar.RTM. Film, Grafix Plastics, Maple Heights, Ohio)
[0107] A 5 inch by 5 inch PSA (pressure sensitive adhesive) coated
on polyester mesh (Lot #16204, Innovize, St Paul, Minn.) was placed
on the polyester substrate of the same dimensions. The two-part
silicone TSA compositions of each of the following examples were
respectively mixed (Example 2, Example 3, and Control Example) and
applied onto the mesh evenly to cover the entire area of the mesh
using a conventional rubber spatula. 5, 1 inch wide specimens were
cut for testing after each of the covered mesh samples were
dried.
[0108] Bio Substrate (Arm of a 55 Year-Old Asian Male)
[0109] A 3 inch by 1 inch PSA (pressure sensitive adhesive) coated
on polyester mesh was placed on the left arm of a 55 year old Asian
male. The two-part silicone TSA compositions of each of the
following examples were respectively mixed (Example 3 and Control
Example) and applied onto the mesh evenly to cover the entire area
of the mesh using a conventional rubber spatula.
[0110] Bio Substrate (Porcine Skin)
[0111] A 5 inch by 1.5 inch PSA (pressure sensitive adhesive)
coated on polyester mesh (Lot #16204, Innovize, St Paul, Minn.) was
placed on a piece of porcine skin with approximately the same
dimension. The two-part silicone TSA composition of examples 3 was
mixed and applied onto the mesh evenly to cover the entire area of
the mesh using a conventional rubber spatula.
[0112] Stretch Test Samples
[0113] A 5 inch by 5 inch PSA (pressure sensitive adhesive) coated
polyester mesh (Lot #16204, Innovize, St Paul, Minn.) was placed on
a Teflon substrate. The two-part silicone TSA composition was mixed
(Example 3) and applied onto the mesh evenly to cover the entire
area of the mesh using a conventional rubber spatula. The silicone
coated polyester mesh was peeled off from the Teflon substrate
after 1 hour. 5, 1 inch-wide silicone coated mesh specimens were
cut for testing.
[0114] Performance Testing Results:
[0115] 1a: Holding Test (Synthetic Substrate)
[0116] Holding test on Polyester film was performed for the
compositions of Example 2 and 3, along with the Control Example;
the results are summarized in Table 1.
TABLE-US-00001 TABLE 1 Sample Holding Strength (lb/in) Example 2
13.4 Example 3 17.9 Control Example 0.7
[0117] Referring to Table 1, it can be seen that the holding force
for the polyester substrate is significantly better in the
inventive examples made from polysiloxane polymer and commercial
bases, compared to conventional cross-linked silicone polymer using
the Karstedt catalyst.
[0118] 1b: Holding Test Results (Bio Substrate)
[0119] Holding test on porcine skin was performed on the
composition of Example 3 and the results are summarized in Table
2
TABLE-US-00002 TABLE 2 Sample Holding Strength (lb) Example 3
10.2
[0120] Referring to Table 2, one sees that the holding force of the
silicone-based TSA on porcine skin is comparable to cyanoacrylate
based commercial product holding strength which is about 10
lbs.
[0121] 2a: Peel Test Results (Synthetic Substrate)
[0122] Peel tests of TSA compositions on a synthetic substrate
(polyester) was performed using the compositions of Examples 2 and
3, along with Control Example and the results are summarized in
Table 3.
TABLE-US-00003 TABLE 3 Average Peel Strength Maximum Peel Strength
Sample (lb/in) (lb/in) Example 2 1.3 2.1 Example 3 2.6 3.1 Control
Example 0.1 0.2
[0123] Referring to Table 3, it is seen that the average and
maximum peel force for polyester substrate is significantly better
in the inventive examples made from polysiloxane polymer and
commercial bases, compared to conventional cross-linked silicone
polymers using the Karstedt catalyst.
[0124] 2b: Peel Test Results (Bio Substrate)
[0125] Peel tests of TSA on human skin was performed on Example 3
and Control Example and the results are summarized in Table 4.
TABLE-US-00004 TABLE 4 Average Peel Strength Maximum Peel Strength
Sample (lb/in) (lb/in) Example 3 2.5 3.5 Control Example 0.1
0.3
[0126] The peel force of silicone TSA made in inventive Example 3
is significantly higher than the Control Example. Also, the peel
force of silicone TSA on human skin is very similar to the peel
force of the same material on polyester substrate (see Table
3).
[0127] 2b: Peel Test Results (Bio Substrate)
[0128] Peel tests of TSA on porcine skin was performed on Example 3
and the results are summarized in Table 4a.
TABLE-US-00005 TABLE 4a Sample Average Peel Strength (lb/in)
Maximum Peel Strength (lb/in) Example 3 0.42 1.04
[0129] 3: Stretch Test Results
[0130] Example 3 was stretched to 160% of its original length. The
dimensions of the testing sample were measured before and after the
stretch and the image was show in FIGS. 2A, 2B and 2c.
[0131] Referring to these figures, the testing results indicate
that Example 3 can be elongated to 160% of its original dimensions
and recover fully. In a separate test not depicted, a cyanoacrylate
coated polyester mesh sample could only be elongated to 101% of its
original dimension. That is a 1% stretch was sufficient to create
permanent deformation.
Examples--Solvent Free (SF)
[0132] In some embodiments, use of organic solvent free mixing
compositions are more desirable. Such embodiments include
situations where contents of a mixing device, such as a dual-barrel
syringe, may be made with a solvent in which contents of the
syringe leak past seals of the syringe or the solvent evaporates.
We have found that suitable compositions are possible without use
of organic solvents by substituting a low molecular weight (3000 to
9000) vinyl terminated polydimethylsiloxane and/or low molecular
weight (3000 to 9000) hydride terminated polydimethylsiloxane. Both
these types of low molecular vinyl terminated or hydride terminated
polydimethylsiloxane compounds have viscosities in the 40-150 cPs
range. We have demonstrated that these solvent free formulations
are capable of lowering viscosity of high viscosity silicone bases
that that have viscosities typically higher than 500,000 and up to
several million centipoise.
[0133] In these embodiments, the Part A compositions will typically
comprise a silicone base (containing vinyl terminated polydimethyl
silicone base polymer and fumed silica particles) ranging from 60
to 95 wt. % when controlling to a Part A viscosity of a 45,000 to
75,000 cPs (or 30 to 100 wt. % when controlling to a Part A
viscosity of a 15,000-45,000 cPs, or 0 to 40 wt. % when controlling
to a Part A viscosity of a 75,000 to 105,000 cPs); 5 to 15 wt. %
3000 to 9000 cPs vinyl terminated polydimethylsiloxane; and 100 to
250 ppm of elemental platinum contributed from the catalyst of this
invention:
Pt[(CH.sub.2.dbd.CH)(CH.sub.3).sub.2Si].sub.2O.(COCH.dbd.CHCO)(C.sub.2H.-
sub.5O).sub.2.
[0134] Part B compositions will typically comprise a silicone base
(containing vinyl terminated polydimethyl silicone base polymer and
fumed silica particles) ranging from 60 to 80 wt. % when
controlling to a Part B viscosity of 45,000 to 75,000 cPs base, (or
0 to 30 wt. % when controlling to a Part B viscosity of
15,000-45,000 cPs base, or 70 to 100 wt. % when controlling to a
Part B viscosity of 75,000 to 105,000 cPs base); 10 to 40 wt. %
polymethylhydro-co-polydimethyl siloxane cross linker; and 3 to 12
wt. % hydride terminated poly dimethylsiloxane.
[0135] Typically, the viscosity of both the Part A and Part B
compositions will independently range between 25,000 and 100,000
cPs prior to mixing and will be of similar viscosity when Part A
and Part B are used in conjunction with each other around a low,
medium or high viscosity level.
Example 1-SF: Novel Platinum Catalyst (Synthesis Procedure)
[0136] 2.7 g of diethyl maleate was mixed with 3.6 g of diethyl
ether and 3.6 g of Gelest SIP 6830.3 (3.0% platinum divinyl
tetramethyldisiloxane complex in vinyl terminated
polydimethylsiloxane, Karstedt catalyst--xylene solvent free) at
ambient temperature for 24 hours. 64.9 g of Gelest SIP 6830.3 was
then added into the above mixture and mixed for an additional 72
hours while the lid of the container remained open. Finally, 928.8
g of vinyl terminated polydimethylsiloxane (Gelest DMS V21) was
added and mixed for an additional 4 hours. The novel platinum
catalyst master batch contains the novel catalyst having 2055 ppm
of elemental platinum with essentially the remainder being vinyl
terminated poly dimethylsiloxane.
Example 2-SF, (Low Viscosity) (15,000 to 45,000 cPs)
[0137] Part A
[0138] 90 g of Elkem 55 experimental base (also known as Elkem
Silbione 4020-55, containing vinyl terminated polydimethyl silicone
base polymer and fumed silica particles) was mixed with 10 g of
Example 1-SF using a high-speed centrifugal mixer (FlackTek DAC150
FV-K) at 3470 rpm for 3 minutes. This composition had a viscosity
of 32,090 cPs (see Example 7a-SF).
[0139] Part B
[0140] 90 g of Elkem 55 experimental base was mixed with 9.0 g of
polymethylhydro-co-polydimethyl siloxane cross linker (Gelest HMS
H301), 3.0 g of SiH terminated polydimethylsiloxane chain extender
(Gelest DMS H21) using a high-speed centrifugal mixer (FlackTek
DAC150 FV-K) at 3470 rpm for 3 minutes. This composition had a
viscosity of 31,160 cPs (see Example 7a-SF).
Example 3-SF, Mid-Viscosity (45,000 to 75,000 cPs)
[0141] Part A
[0142] 115 g of Elkem 55 experimental base was mixed with 20 g of
Elkem 44 experimental base (also known as Elkem Silbione 4020-44,
containing vinyl terminated polydimethyl silicone base polymer and
fumed silica particles) and 15 g of Example 1-SF using a high-speed
centrifugal mixer (FlackTek DAC150 FV-K) at 3470 rpm for 3 minutes.
This composition had a viscosity of 57,900 cPs (see Example
7a-SF).
[0143] Part B
[0144] 80 g of Elkem 44 experimental base was mixed with 20 g of
Elkem 55 experimental base, 42 g of polymethylhydro-co-polydimethyl
siloxane cross linker (Gelest HMS 151), 8.0 g of SiH terminated
polydimethylsiloxane chain extender (Gelest DMS H21) using a high
speed centrifugal mixer (FlackTek DAC150 FV-K) at 3470 rpm for 3
minutes. This composition had a viscosity of 61,500 cPs (see
Example 7a-SF).
Example 4-SF, High Viscosity (75,000 to 105,000 cPs)
[0145] Part A
[0146] 90 g of Elkem 55 experimental base was mixed with 45 g of
Elkem 44 experimental base and 15 g of Example 1-SF using a
high-speed centrifugal mixer (FlackTek DAC150 FV-K) at 3470 rpm for
3 minutes. This composition had a viscosity of 84,000 cPs. (see
Example 7a-SF).
[0147] Part B
[0148] 100 g of Elkem 44 experimental base was mixed with 42 g of
polymethylhydro-co-polydimethyl siloxane cross linker (Gelest HMS
H151), 8.0 g of SiH terminated polydimethylsiloxane chain extender
(Gelest DMS H21) using a high-speed centrifugal mixer (FlackTek
DAC150 FV-K) at 3470 rpm for 3 minutes. This composition had a
viscosity of 94,800 cPs (see Example 7a-SF).
Example 5-SF: Preparation of Adhesion Performance Test Samples
[0149] Holding Strength Test Sample
[0150] Synthetic Substrate, Polyester Film (0.05 Inch Thick
Duralar.RTM. Film), Grafix Plastics, Maple Heights, Ohio
[0151] A 1.5 inch wide PSA (pressure sensitive adhesive) coated
polyester mesh (Lot #16204, Innovize, St Paul, Minn.) was placed
along the cutting line to hold together the two half pieces of the
Duralar film of 4 inches by 11 inches described above. The two-part
silicone TSA compositions in each of the following examples were
respectively mixed (Example 2-SF, Example 3-SF, Examples 4-SF) and
evenly applied onto the mesh to cover the entire area of the mesh
using a conventional rubber spatula. The samples were cured between
1 to 3 minutes at 31 deg C. and maintain at this temperature
overnight. 5 pieces of 1 inch wide strips of each of the covered
mesh samples were cut for testing.
[0152] Peel Test Sample
[0153] Synthetic Substrate (Polyester Film, 0.05 Inch Thick
Duralar.RTM. Film, Grafix Plastics, Maple Heights, Ohio)
[0154] A 5 inch by 5 inch PSA (pressure sensitive adhesive) coated
on polyester mesh (Lot #16204, Innovize, St Paul, Minn.) was placed
on the polyester substrate of the same dimensions. The two-part
silicone TSA compositions of each of the following examples were
respectively mixed (Example 2-SF, Example 3-SF, Examples 4-SF) and
applied onto the mesh evenly to cover the entire area of the mesh
using a conventional rubber spatula. 5, 1 inch wide specimens were
cut for testing after each of the covered mesh samples were cured
and maintained at 31 deg C. over night (i.e., at least 8
hours).
[0155] Stretch Test Samples
[0156] A 5 inch by 5 inch PSA (pressure sensitive adhesive) coated
polyester mesh (Lot #16204, Innovize, St Paul, Minn.) was placed on
a polyethylene substrate. The two-part silicone TSA composition was
mixed (Examples 2-SF, 3-SF and 4-SF) and, applied onto the mesh
evenly to cover the entire area of the mesh using a conventional
rubber spatula. The silicone coated polyester mesh was peeled off
from the Teflon substrate after 1 hour. 5, 1 inch-wide silicone
coated mesh specimens were cut for testing.
Example 6-SF. Description of Testing Procedures
[0157] Viscosity Measurement:
[0158] Viscosity measurements were performed on Examples 2-SF, 3-SF
and 4-SF, using a Brookfield DV II+CP viscometer. Spindle 12 was
used for all measurements and the speed was 1 RPM.
[0159] Cure Time Measurement
[0160] ASTMC679: Standard test method for tack-free time of
elastomeric sealants. The test consists of lightly touching a
surface of a curing sealant with a polyethylene film at regular
intervals until the sealant does not attach itself to the film and
the film appears clean when peeled from the surface. More
specifically a strip of polyethylene film is placed on the surface
of the curing elastomer and a 30 g weight is placed on the film.
The weight is left in place for 30 seconds, then removed and the
polyethylene strip is removed and examined for sealant attachment
to the film. The length of time from when the sealant was first
applied onto a given surface until the time the sealant is no
longer picked up by the film is call tack-free time and is the time
point at which the film exhibits a non-tacky nature which evidences
that the sealant has cured.
[0161] Peel Test.
[0162] The T-peel strength test was performed following ASTM F2256:
Standard test method for Strength Properties of Tissue Adhesives in
T-Peel by Tension Loading.
[0163] The average peel strength of mesh coated with silicone-based
TSA in T-peel configuration is performed at a strain rate of 10
inches per minute.
[0164] Holding Strength Test:
[0165] This test evaluated the force required to separate the
substrate approximated with the PSA coated mesh and the applied
silicone TSA compositions. This method was based on ASTMF2458:
Standard test method for wound closure strength in tissue adhesive
and sealant.
[0166] Synthetic substrate (Mylar) was used for the test. The width
of the synthetic substrate was 1 inch and the strain rate was 20
inches/minute.
Examples 7-SF. Performance Testing Results
[0167] 7a-SF. Viscosity Measurement.
[0168] The result of viscosity measurements of Examples 2-SF, 3-SF
and 4-SF are summarized in Table 1a-SF.
TABLE-US-00006 TABLE 1a-SF Sample Part A Viscosity (cPs) Part B
Viscosity (cPs) Example 2-SF 32090 31160 Example 3-SF 57900 61500
Example 4-SF 84000 94800
[0169] 7b-SF. Cure Time Measurement
[0170] Cure time measurements were performed for the compositions
of Examples 2-SF, 3-SF and 4-SF, during peeling test sample
preparation; the results are summarized in Table 1b-SF.
TABLE-US-00007 TABLE 1b-SF Sample Cure Time (sec) Example 2-SF 110
Example 3-SF 90 Examples 4-SF 70
[0171] The foregoing demonstrates that the inventive compositions
are able to cure under 2 minutes.
[0172] 7c-SF: Holding Test Results (Synthetic Substrate)
[0173] Holding test on Polyester film was performed for the
compositions of Example 2-SF, 3-SF and 4-SF; the results are
summarized in Table 1c-SF.
TABLE-US-00008 TABLE 1c-SF Sample Holding Strength (lb/in) Example
2-SF 11.5 Example 3-SF 14.9 Example 4-SF 15.2 Control Example (see
Table 1) 0.7
[0174] Referring to Table 1c-SF, it can be seen that the holding
force for the polyester substrate is significantly better in the
inventive examples made from polysiloxane polymer and commercial
bases, compared to conventional cross-linked silicone polymer using
the Karstedt catalyst (Control Example, Table 1).
[0175] 7d-SF: Peel Test Results (Synthetic Substrate)
[0176] Peel tests of TSA compositions on a synthetic substrate
(polyester) was performed using the compositions of Examples 2-SF,
3-SF and 4-SF. The results are summarized in Table 1d-SF.
TABLE-US-00009 TABLE 1d-SF Sample Average Peel Strength (lb/in)
Example 2-SF 1.2 Example 3-SF 1.5 Example 4-SF 1.6 Control Example
(See Table 3) 0.1
[0177] Referring to Table d-SF, it is seen that the average peel
force for polyester substrate is significantly better in the
inventive examples made from polysiloxane polymer and commercial
bases, compared to conventional cross-linked silicone polymers
using the Karstedt catalyst. (Control Example, Table 3)
[0178] 7e-SF: Stretch Test Results
[0179] Examples 2-SF, 3-SF and 4-SF were able to be stretched to
160% of its original length and recover to its original
dimensions.
[0180] As demonstrated, the novel compositions, wound closure
systems and catalyst of the present invention have many advantages
compared with the prior art. The compositions allow for the
formation of medical grade silicone adhesive, in particular
suitable for human skin. The compositions provide a durable elastic
structure, which provides both mechanical properties and adhesion
properties. The catalyst provides dual cured catalytic action,
enabling the cross link of polysiloxane chains to form a film
rapidly while forming adhesion properties on a given hydroxyl
containing substrates. The silanol functions on the surface of
silicone fillers in the compositions reacts with the hydroxyl
functions on a given surface in the presence of this novel dual
functional catalyst provide the adhesion properties on this novel
silicone based adhesive.
[0181] Although this invention has been shown and described with
respect to detailed embodiments thereof, it will be understood by
those skilled in the art that various changes in form and detail
thereof may be made without departing from the spirit and scope of
the claimed invention.
* * * * *